1. Field of the Invention
The present invention relates to a pixel and an organic light emitting display using the same, and in particular to a pixel capable of compensating for deterioration of an organic light emitting diode and an organic light emitting display using the same.
2. Description of Related Art
Recently, various flat panel display devices with reduced weight and volume have been developed. Examples of flat panel display devices include liquid crystal displays, field emission displays, plasma display panels, and organic light emitting displays.
An organic light emitting display displays an image using an organic light emitting diode (OLED), which generates light through recombination of electrons and holes. Such an organic light emitting display has a high response speed and low power consumption.
FIG. 1 is a circuit view showing a pixel of a conventional organic light emitting display described in Korean Patent Registration No. 10-0815756. Referring to FIG. 1, a pixel 4 of the conventional organic light emitting display includes an OLED and a pixel circuit 2 coupled to a data line Dm and a scan line Sn to control the OLED.
An anode electrode of the OLED is coupled to the pixel circuit 2, and a cathode electrode of the OLED is coupled to a second power supply ELVSS. Such an OLED generates light with a luminance corresponding to current supplied from the pixel circuit 2.
The pixel circuit 2 controls the amount of current supplied to the OLED corresponding to a data signal supplied to the data line Dm when a scan signal is supplied to the scan line Sn. The pixel circuit 2 includes a second transistor M2, a first transistor M1, and a storage capacitor Cst. The second transistor M2 is coupled between a first power supply ELVDD and the OLED. The first transistor M1 is coupled between the second transistor M2, the data line Dm, and the scan line Sn. The storage capacitor Cst is coupled between a first electrode and a gate electrode of the second transistor M2.
A gate electrode of the first transistor M1 is coupled to the scan line Sn, and a first electrode of the first transistor M1 is coupled to the data line Dm. A second electrode of the first transistor M1 is coupled to one terminal of the storage capacitor Cst. The first electrode is a source electrode or a drain electrode and the second electrode is a different electrode from the first electrode. For example, if the first electrode is the source electrode, the second electrode is the drain electrode. The first transistor M1 coupled to the scan line Sn and the data line Dm is turned-on when the scan signal is supplied from the scan line Sn to supply the data signal supplied from the data line Dm to the storage capacitor Cst. The storage capacitor Cst is then charged with a voltage corresponding to the data signal.
The gate electrode of the second transistor M2 is coupled to one terminal of the storage capacitor Cst, and the first electrode of the second transistor M2 is coupled to the other terminal of the storage capacitor Cst and the first power supply ELVDD. The second electrode of the second transistor M2 is coupled to the anode electrode of the OLED. Such a second transistor M2 controls the amount of current flowing from the first power supply ELVDD to the second power supply ELVSS via the OLED corresponding to a voltage value stored in the storage capacitor Cst. The OLED generates light corresponding to the amount of current supplied from the second transistor M2.
However, there is a problem that the conventional organic light emitting display cannot display an image with desired luminance when there is an efficiency change as a result of deterioration of the OLED. In other words, the OLED degrades with time and the conventional organic light emitting display cannot display an image with a desired luminance as a result of the degradation. Effectively, light with low luminance is generated as the OLED degrades.